1. Field of Invention
The present invention relates to a display apparatus. More particularly, the present invention relates to a display apparatus and a method for controlling the same which improves a process for generating an on-screen-display (OSD) menu.
2. Description of the Related Art
In general, as a typical display apparatus, the television receives broadcast signals through an antenna or receives image signal from a TV card and displays the received image signals. Recently, televisions which can receive and display image signals from various external signal generation sources such as video tape recorders (VTR), video camcorders, set top boxes (STB) and the like have become popular. Furthermore, televisions which can be used as a computer monitor displaying a PC image signal having a high resolution and received from a computer main body have become available. In televisions that can display image signal received from various external signal generation sources, one or more processors are required for processing various kinds of image signals received from various external signal generation sources in view of a resolution of the image signal.
A conventional television for displaying an image signal received from various external signal generation sources is illustrated with reference to FIG. 1 below. As shown in FIG. 1, the television comprises a signal processing unit 10, a second scaler 20 and a display unit 22.
According to recent trends, the signal processing unit 10 comprises an image decoder 2, a first scaler 4, an on-screen-display (OSD) generation unit 6 and a mixer 8 which are preferably fabricated on a single chip. An image signal received from an external source is processed in the image decoder 2 and the first scaler 4, the processed image signal is outputted to the second scaler 20.
In general, image signals can be broadcast signals, image signals received from a video player or the digital video disk (DVD) player, and they can be standard definition (SD) image signals or high definition (HD) image signals. Such image signals are analog-to-digital (A/D) converted or decoded into an image signal suitable for display on the display unit.
The second scaler 20 processes image signals having a high resolution which can not be processed in the signal processing unit 10. The second scaler 20 receives and processes the typical high resolution PC image signal and outputs the processed signal to the display unit 22. Also, the second scaler 20 can simply pass the image signal outputted from the signal processing unit 10 to output the image signal to the display unit 22. In addition, the second scaler 20 can perform an additional process (for example, panorama, letterbox, and so on) to process the image signal with a final format to be displayed.
Accordingly, in the conventional television, once a standard resolution image display of the image signal is selected according to the user's selection, the image signal is passed in the signal processing unit 10 and the second scaler 20, and then displayed on the display unit 22. If the display of high resolution PC image signals is selected, the image signal is passed in the second scaler 20 and then displayed on the display unit 22.
Here, once a signal for the generation of an on screen display (OSD) menu is received in the process of processing the image signal inputted to the signal processing unit 10 in order to display an image of the image signal having the standard resolution, the OSD generation unit 6 generates and outputs the OSD menu signal. Accordingly, the mixer 8 outputs a prescribed image signal obtained by synthesizing the image signal outputted from the first scaler 4 and the OSD menu signal outputted from the OSD generation unit 6 to the second scaler 20, this image signal is passed in the second scaler 20 and then displayed on the display unit 22 as the image including the OSD menu.
In general, however, the second scaler 20 of the conventional television as described above does not include a function for synthesizing two image signals like the mixer 8. Therefore, conventional televisions have a problem in that once the signal for generation of the OSD menu is received in the process of processing the PC image signal inputted to the second scaler 20 in order to display a high resolution PC image signal, although the OSD generation unit 6 in the signal processing unit 10 generates and outputs the OSD menu signal, the second scaler 20 does not synthesize the OSD menu signal and the PC image signal, and so the OSD menu is not displayed on the display unit 22 along with the PC image signal.
In order to solve the above mentioned problem, a structure in which an independent chip (not shown) is additionally provided in addition to the OSD generation unit 6 can be used. However, this is not an optimal solution since it requires additional cost to add an additional chip, and also because there is no unity of the menu screens due to a difference between the OSD menu screens obtained when the image with the standard resolution and the image with the high resolution are displayed. An appearance difference is generated by a variation of resolution and definition of image according to a performance of the processor.